Recently, the organic light emitting diode (OLED) display become a very popular flat display product worldwide due to OLED display panel's self-luminosity, wide view angle, short responsive time, high light emitting efficacy, wide color gamut, compact size, large-side display compatibility, flexibility, simple manufacturing process and the potential of low cost.
In OLED display panel, the AMOLED display panel is one of major technologies of flexible display. However, the luminous uniformity and the after-image are two major issues to be overcome in AMOLED technology, IR drop is one of the factors causing these two major issues. Due to the resist of the powerline (metal made), the current pass through the powerline with a certain voltage drop, which is so call “IR drop”. IR drop would cause the voltage applied at the point near the power differs the voltage applied at the point away from the power. The current of the OLED device is related to the voltage applied on the powerline. Therefore, the IR drop would cause the different areas connected to the powerline have different currents so that the luminosity is not uniform and the display quality is affected. The IP drop is one of the major issues to be solved while designing the display panel.
FIG. 1 is the powerline layout of the conventional AMOLED. In FIG. 1, the two terminals of the chip 1 are connected with an anode 2 with a positive voltage Vdd and a cathode 3 with a negative voltage Vss. The positive powerline 21 is connected with the anode 2 and extending to the display areas in the display panel. A plurality of the positive powerlines 21 are arranged in parallel, and negative powerline 31 is connected with a cathode 3 and extending to the non-display area. As mentioned above, the voltage applied on the positive powerline 21 and the negative powerline 31 are different so that the currency in different areas of the OLED device is different as well. The luminosity of the display panel is not uniform so that the display quality is affected.